Daniel deawbaugh



(No Mdel D. DRAWBAUG'H.' TELEPHONE TRANSMITTER.

;1\I0.-29o,930. t Patented De0. 25, 1883.

WITNESSES Unir-ED STATES PATENT trice.

DANIEL DRAVBAUGH, OF EBERLYS MILL, PENNSYLVANIA.

TELEPHONE-TR'ANSM iTT'ER.

SPECIFICATION forming part of Letters Patent No. 290,980, dated December 25,' 1883.

appncnaion moa May 15, lsf-:3. (No mom-1i To a/ZZ whom it may concern'.-

Be it known that I, DANIEL DRAWBAUGH,

` of .'Eberlys Mill, Cumberland county, Pennphone-.transmitters :in which a current is modilied and rendered capable of transmitting articulate speech by passage through pieces of low conducting material in contact.

vThe invention consists in the construction of the instrument more particularly hereinafter set forth, and in the devices described whereby the initial pressure between carbons may be adj usted with great delicacy.

vIn the accompanying drawings, Figure lis a front view of the instrument with the diaphragm and cover removed. Fig. 2 is a vertical section on line X X of Fig. 1'. Fig. 3 is a rear view of the diaphragm with the carbons and carbon-holder attached. Fig. 4 is a vertical section of l[he carbons, the movable carbon being shown in enlarged section on the line Y Y of Fig. 3.

Similar letters of reference indicate like parts.

A is the base or back board of the instrument. B is the inclosing-case. C is the cover, having a mouth-piece orifice, F, and D is the diaphragm, here shown constructed of wood or other non-conducting material.

To the rear side of the diaphragm, and at about its center, is secured a metal bracket, E. To said bracket is pivoted a metal cup, G, which contains a piece of carbon, H, or other low conducting material, in the form of a hollow cylinder. Y

Within the carbon H loosely ts a solid cylinder, I, of carbon or other low conducting material, having a rounded lower end.

To the base-board of the instrument is secured a third piece. L, of carbon or other low conducting material, which is secured to said base by metal brackets J K. The front side of the carbon L isl rounded or made concave, substantially as shown in Figs. 2 and 4.

Rigidly secured toan offset, M, of the cup vG is a rod or shaft, N, which extends horizontally through an opening, O, in the side of the case, and at its outer end it is provided with a lever, P. i. Said shaft N passes through the bracket E, and has a lint or enlargement at its end, so that it serves as a pivot between the cup G and bracket E.v By moving the lever 5 5 l? the inclination of the cup G, and consequent` ly of the carbons therein contained, may be changed as desired. As the cup G more nearly l'approaches a vertical position wthe carbon I slides out of the carbon H and rests with a 6o greater proportion of its weight against the concave or cam surface of the carbon L. O11 the other hand, when the cup G is turned toward ahorizontal posit-ion, the carbon I, by its contact with the concave face of carbon L, is forced into the carbon H, so that a less proportion of its weight is sustained by the carbon L. It will further be apparent that as the cup G is turned vertically, and, as already described, more of the weight of the carbon I 7o comes on the carbon L, less of that weight will fall upon the inclosing-carbon H, while at the same time the area of contact between the carbon I and carbon H will be lessened, owing to the sliding of the carbon I out of the carbon H. So, conversely, when the cup G is turned into a horizontal position, less of the weight of the carbon, I will fall on the carbon L, while more of it will be sustained by the carbon H, and at the same time there will be a greater 8o area of contact between carbon I and carbon H, owing to the sliding of the former into the latter. It will bev apparent from the foregoing that there is always a light and delicate contact between two carbons of the tliifeand that this may be varied with great delicacy through what may be regarded as the differential disposition of the weight of the solid carbon cylinder upon the other carbons as their rela- 9o tive adjustment is changed, so that,the initial pressure between the electrodes in the telephone may be regulated with the utmost nicety to give the best result by simply moving the lever P.

The circuits in the instrument proceed as follows: from the battery to the binding-post 1, to the spring` Q, to the plate It, and thence by wire to the contact-plate S. When the diaphragm is in place, a plate, T, on said diaphragm comes in contact with the plate S, and the current is conducted from the plate IOO T, by the wire a, to the bracket E, cup G, earbons H I, carbon L, bracket J, wire Z), to the primary of the induction-coil II, thence by wire c to the binding-post 2, and thence back to the battery. The secondary wires 7 c of the coil U lead to posts 71 i, which posts communicate by wiresj l: with thc line bindingposts 3 l, and also by branch wires l m to the binding-posts 5 6, to which a recei\inginstrument may be con nectcd.

V is a pin on which a receiving-instrument may be hung when not in use, in which case the ring in said instrument presses upward the downward projection \V ot the spring Q, and breaks Contact between the springs Q and It.

I claim as my inventionq l. Ina telephonc-transmitter, and in combination with the diaphragm thereof, a moyable hollow cylinder of low conducting material, a. solid cylinder of low conducting material iitting loosely in said hollow cylinder, and a ixed piece or block of low conducting material, against which the end of said solid cylinder rests in Contact by gravity, and a means for varying thc inclination of said hol4 low cylinder, substantially as described.

2. In a telephone-transmittcr, the combisaliese natiolrol" a diaphragm, a support pivoted or hinged to said diaphragm, a hollow cylinder of low conducting material contained in said support, a solid cylinder of low conducting material litting in said hollow cylinder, and a xed piece or block of carbon, against which the lower end of said solid cylinder rests in contact by gravity, substantially as described.

3. In a telephone-transmitter, thc colnbination of a diaphragm, a hollow cylinder ot` low conducting material hinged or piyoted thereto, ay solid cylinder of low conducting material loosely fitting in said hollow cylinder. and a lixcd cam, against the surface ot' which the lower end ot' said solid cylinder rests by grayity, and which, when said hollow cylinder is yibratcd in one direction, forces thc solid cylinder into the hollow cylinder, snb

stantially as described.

l l l t 1 et. In a telcphone-transmitter, the combination of the diaphragm l), bracket IG. cup G, shaft N, a means of rotating said shaft, car- D( bon II, carbon I, and carbon L, substantially as described.

I) A NI EL DR fVBAUGl-l. W'itnesses:

FRED. )L O'r'r, )L XV. .T wons. 

